This invention relates to a method and apparatus for coating glass.
It has previously been proposed to coat flat glass by contacting the glass with a gaseous coating material at substantially atmospheric pressure. However, it has been difficult to achieve uniform coatings on a moving glass ribbon by known techniques. In U.S. Pat. No. 3,850,679, it is proposed to enhance the uniformity of films produced by chemical vapour deposition by directing coating gas onto the glass surface through a nozzle at a Reynolds number of at least 2,500. For high speed coating a continuous ribbon or sheet of glass, a Reynolds number of at least 5,000 for the flowing gas is recommended. The use of a Reynolds number above 2,500 means that the gas flow is turbulent.
In contrast, it has now been found that uniform coatings may be formed by causing a coating gas to flow substantially parallel to the surface of a moving ribbon of glass to be coated under laminar flow conditions as opposed to turbulent flow conditions.